Cement screed floor: the appointment, laying, calculation of components

And the premises belonging to the old housing stock, and completely new, recently commissioned apartments rarely can boast a flat floor. Accordingly, the issue of updating and improving the quality of the floor is quite relevant for both residential and industrial facilities. To tie up the floor of the room helps screed. It can be of different types, knowing the features of which you can choose the technology that is ideally suited in a particular case.

Content:

• 1 Types of screeds and their functions
• 2 Cement for screed: how to calculate the required quantity?
• 3 Cement screed: pouring rules
  • 3.1 Basic rules to follow when leveling the floor
• 4 How to increase the strength of the screed?

Types of screeds and their functions

Any type of floor screed can perform the following functions:

• level the surface;
• increase the rigidity and strength of structures;
• strengthen sound and heat insulation of an apartment, house;
• create the required angle of inclination of the surface;
• raise the floor level;
• distribute the load evenly over the entire surface area.

Thus, we can say that the floor screed refers to the technological processes that allow for further finishing finish to achieve a completely flat surface. In the 20th century, only one type of screed was used, which has not lost its relevance so far. However, at present there are completely new types of leveling the floor, differing from one another by styling technology and potentially possible objects on which they can be used.

Modern floor screed happens:

• Concrete or cement. As a rule, it is used at primary alignment of a surface. Perfectly eliminates large bumps and floor drops. Laying technology is extremely simple, but requires some physical costs.
• Self leveling Performed by the new technology with the use of special ready-made mixtures. It can be laid under any covering. The thickness of this screed is up to 3 cm.
• Dry. It is used to level small unevenness of the floor with the help of special hard materials. There are two ways to do this tie:
  - alignment on logs. It is rather laborious and complicated process, requiring specification and availability of certain knowledge. The surface in this case is leveled with solid sheets of chipboard, plywood or other materials, which are placed on a system of log specially created from wood;
  - alignment with gypsum-fiber sheets. It is performed fairly quickly, does not require specific knowledge. However, it should be borne in mind that on such a floor covering loads must be properly distributed.

Find out where white cement is used.

Detailed article on the proportions of cement. Proper storage in large volumes http://o-cemente.info/cement/silos-dlya-cementa-vidy-xaraktiristiki.html

Cement for screed: how to calculate the required quantity?

The ratios of sand and cement for floor screed depend on the brand of material used. You can use the following table to calculate proportions:

Usually for floor screed held in apartments, a solution of mark 200 or 150 is used.

To calculate the specific amount of the required materials is possible by conducting mathematical calculations. For example, in order to pour a 5-cm tie on an area of ​​40 m2 in size, we first calculate the required number of cubic meters of the mixture:

40 m2x 0.05 m = 2.0 cubic meters of the mixture.

Since the ratio of sand and cement should be about 3 to 1, then sand will need at least one and a half cubes. This is calculated in this way - in two cubic meters of the mixture three parts of sand (or can also be written as a fraction) and one part of cement ( 1/4):

2.0 (cubic meters) x ¾ (sand) = 1.5 cubic meters.

Cement is required 0.5 m3. This can be calculated using the same formula:

2.0 cubic meters x ¼ (cement) = 0.5 cubic meters.
Now we calculate the specific amount of each material. For this we need the following table:

We consider cement: 0.5 (cubes) x 1300 (1400) kg = 650 (700) kg.

Consider the sand: 1.5 cubes x 1400 (1600) kg = 2100 (2400) kg.

Another very important fact that must be considered in the calculations: in the process of creating a concrete mass, the volume of the mixture is significantly reduced. This happens due to the fact that the smallest particles of the filler fill the voids. Thus, from one cubic meter of dry mix you can get from 0.59 to 0.71 m3 of concrete mass. Accordingly, the preparation of a cubic meter of concrete mass will require much more dry materials.

For example, for concrete of the same composition is required:
sand - 0.445 m3, gravel - 0.870, cement - 0.193 m3 (250 kg) and water - 178 l.

For another composition is required:
sand - 0.395 m3, gravel - 0.880, cement - 0.198 m3 (260 kg) and water - 185 l.

For the third composition is required:
sand - 0.445 m3, gravel - 0.880, cement - 0.204 m3 (265 kg) and water - 189 l.

Cement screed: pouring rules

If you are going to level the floor, you should not forget that the screed must meet the following quality indicators:

1. The finished floor must withstand the required loads.
2. Under the screed must be waterproofing of any kind.
3. Waterproofing coating must also be applied on the walls - in the height of the planned screed.
4. The floor is leveled in one day in order not to disturb the density of the working solution.
5. If it is planned that the screed will mask communications systems, then its height above the pipes should be at least 2 centimeters.
6. The leveling layer, which is laid on top of the warm floor, should be 5 cm.

The criterion of high quality work is the absence of chips and cracks. If the damage is present in large quantities, then leveling the floor will have to be done again. And not too noticeable shortcomings can be perfectly corrected with the help of cement-sand mixture.

For holding the floor screed and working with concrete or cement mortars, you will need tools such as a tape measure, trowel, rule, trowel, level (level), knife, beacons, drill with nozzle (mixes the mixture) and a special container in which the working solution will be prepared.

Basic rules to follow when leveling the floor

• The screed is done exclusively on a clean basis, so you need to carefully inspect the old screed and assess its condition. If the floor is strong enough and does not crumble, then you can safely pour the cement mortar on top. If the old screed in poor condition, then it is necessary to get rid of it. This can be done using a bump stop or a perforator. After that, it will be necessary to completely remove dirt and dust from the surface.
• Before pouring it is necessary to check the joints of the floor and walls. If necessary, the joints should be treated with mounting foam - this will prevent leakage of the solution to the neighbors.
• Plasticizers can improve the properties of a concrete mortar. These substances to some extent prevent the occurrence of cracks on the already prepared base.
• Immediately before applying the solution, the entire base must be moistened with plain water.
• Pour ready solution, starting from the far corner of the room.
• During the alignment, the solution must be shaken, thus removing air bubbles from it. If for some reason it is impossible to shake it, then you can simply pierce the solution in several places with wire.
• After laying a cement or concrete screed, it is prohibited to ventilate the room until the solution hardens completely. In order to avoid annoying errors, you should carefully study the instructions on the packaging of cement or the corresponding mixture.

How to increase the strength of the screed?

In order to increase the strength of the floor, when the screed is placed in its body, a metal mesh is embedded in the body, which guarantees the absence of cracks. The solution is most often created from sand-mixed sand concrete. Before mixing the solution you should pay attention to the color of the dry mixture - it should be a uniform gray tint, without yellow, red and brown inclusions, indicating an excess of sand.

Experts advise not to add too much water to the solution - only in this case, the strength of the screed will be quite high. You can also improve the working solution with special additives that increase the plasticity and facilitate the alignment of the screed.

When the filling has already been done and its surface is aligned with the beacons, the solution must be allowed to dry (the desired level of humidity is maintained by daily sprinkling with plain water) and remove the beacons. Most often this happens on the second day after pouring. The traces left from the lighthouses, ground and rubbed with fresh solutions.

It is recommended to monitor the condition of the screed for ten days. In this case, the laid surface must be further daily moistened with water, preventing the drying of the concrete and its cracking.